A small homemade bomb has exploded outside a French church in Rome, ahead of a visit to the Vatican by the country's president Francois Hollande.

The blast happened at about 2.30am local time (1:30 GMT) in Vicolo della Campana, which contains the Saint-Yves des Bretons church, part of a French religious foundation, and a restaurant.

The French embassy said the explosion could be linked to Mr Hollande's visit for his first meeting with Pope Francis at the Vatican, which comes with the president in the spotlight over an alleged affair with an actress.

An official at the embassy said: "One of the theories is that this act was linked to the visit by the president."

However, despite tight security the private meeting went ahead as scheduled. A high-level prelate told AFP he expected the conversation to be "no holds barred".

Image Caption:Francois Hollande speaks with Pope Francis at the Vatican

In a statement after the meeting the Vatican said the two talked about "constructive cooperation for the common good" and "family, bioethics and the respect of religious communities".

Syria was also on the agenda. Mr Hollande asked Pope Francis to receive the country's main opposition group, the Syrian National Coalition.

The Carabinieri military police said no one was injured in the bombing, which no one has claimed responsibility for. Residents in the neighbourhood said they thought the explosion might be linked to a nearby nightclub they said has ties to the Mafia.

A number of windows were shattered and three cars parked on the street outside were damaged by the bomb, which contained bits of metal and explosive powder.

Image Caption:A carabiniere outside the church in Rome

Bomb disposal experts were called out again later on Friday after receiving an anonymous phone call about a bomb under the famous colonnade at St Peter's Square. It turned out to be a false alarm.

Mr Hollande's visit to Rome comes as First Lady Valerie Trierweiler confirmed she would travel to India on Sunday after being hospitalised following the magazine revelations about the president's relationship with actress Julie Gayet.

The two-day trip was organised by French relief organisation Action Against Hunger and had been planned long in advance.

Mr Hollande has acknowledged "painful moments" in his relationship with Ms Trierweiler and has said he will clarify his domestic situation before a February 11 state visit to Washington, during which she would have been expected to accompany him.

He is deeply unpopular at home and hopes the Vatican visit could reconcile him with a Catholic electorate largely hostile to his policies.